Veroneau said that the US commitment to free trade in "recreational services" was not intended to included Internet gambling, which did not exist at the time.
The commitment to opening up recreational services "doesn't explicitly include gambling nor does it necessary exclude it," Veroneau said.
"It didn't occur to us that this could include gambling until Antigua brought this case in 2003."
"Clearly that was an oversight in the drafting," he said.
"The process we are starting today would allow us to clarify our schedule and make clear that we did not intend and do not intend to have gambling included in our services agreement."
US officials said Article 21 of the GATS agreement allows a member to file clarifications to their original schedule of commitments, a procedure that has been used only once.